Willamette River

The Willamette River (pronounced wɨˈlæmɨt) is a tributary of the Columbia River. The name of the river derived from the French pronunciation of the name of a Clackamas Indian village. The river is 187 mi long, lying entirely in northwestern Oregon in the United States. Flowing northward between the Oregon Coast Range and Cascade Range, the river and its tributaries form a basin called the Willamette Valley containing two-thirds of Oregon's population, including its largest city Portland, which sits along both sides of the river near its mouth on the Columbia, Portland is divided by the Willamette into east and west sides. Its lush valley is fed by prolific rainfall on the western side of the Cascades, forming one of the most fertile agricultural regions of North America that was the destination for many if not most of the immigrants along the Oregon Trail. The river was an important transportation route throughout much of the early history of the state, furnishing a means of conveying the vast timber and agricultural resources of the state to the outside world.

In Harrisburg, the average depth of the river is approximately 20 ft and 50 ft maximum river depth. In Portland, the average depth of the river is 65 ft and maximum depth of the river is 130 ft.

Part of the river's floodplain (the Willamette Floodplain) was established as a National Natural Landmark in 1987; ten years later the river was named as one of ten national American Heritage Rivers.